The decoloring apparatus carries out erasing of the color of the coloring material (developing material) so as to erase the color of the image and to enable reuse of the paper sheet on which the coloring material has been formed.
To erase an image, the decoloring apparatus heats the developed coloring material (developing material) so as to decrease the effect of the developing agent on the coloring compound (the precursor compound of the coloring matter) that causes display of the color under the action of the developing agent. As a result, the coloring state is cancelled. As used herein, color includes a material having a reflected wavelength, when received by the human eye, within the range of wavelengths discernible by the eye as a color, as well as black and white (when formed on a non-white back ground).
However, when the thermal capacity of a decoloring apparatus is increased to shorten the warm-up time thereof, the power consumption increases during the decoloring process, because the decoloring process may not require the higher thermal capacity function, resulting heat loss, and thus energy loss, resulting from operating the apparatus at a higher than necessary temperature. On the other hand, where a decoloring apparatus merely has the thermal capability required to maintain the temperature required for the decoloring process, the warm-up time of the apparatus will be too long.